Equilibria between Ti oxides and silicate melt lead to Ti isotope fractionation in terrestrial samples, with isotopically light Ti oxides and isotopically heavy coexisting melt. However, while Ti is mostly tetravalent in terrestrial samples, around 10% of the overall Ti is trivalent at fO₂ relevant to lunar magmatism (~ IW-1). The different valences of Ti in lunar samples, could additionally influence Ti stable isotope fractionation during petrogenesis of lunar basalts to an unknown extent. We performed an experimental approach using gas mixing furnaces to investigate the effect of Ti oxide formation at different fO₂ on Ti stable isotope fractionation during mare basalt petrogenesis. Two identical bulk compositions were equilibrated simultaneously during each experiment to guarantee comparability. One experiment was investigated with the EPMA to characterize the petrology of experimental run products, whereas the second experiment was crushed, and fabricated phases (i.e., oxides, silicates and glass) were handpicked, separated and digested. An aliquot of each sample was mixed with a Ti double-spike, before Ti was separated from matrix and interfering elements using a modified HFSE chemistry. Our study shows fO₂-dependent fractionation within seven samples from air to IW-1, especially ∆⁴⁹Ti_{armalcolite-melt} and ∆⁴⁹Ti_{armalcolite-orthopyroxene} become more fractionated from oxidized to reduced conditions (− 0.092 ± 0.028- − 0.200 ± 0.033 ‰ and − 0.089 ± 0.027- − 0.250 ± 0.049 ‰, respectively), whereas ∆⁴⁹Ti_{orthopyroxene-melt} shows only a minor fractionation (− 0.002 ± 0.017-0.050 ± 0.025 ‰). The results of this study show that Ti isotope fractionation during mare basalt petrogenesis is expected to be redox dependent and mineral-melt fractionation as commonly determined for terrestrial fO₂ may not be directly applied to a lunar setting. This is important for the evaluation of Ti isotope fractionation resulting from lunar magmatism, which takes place under more reducing conditions compared to the more oxidized terrestrial magmatism.

氧化钛和硅酸盐熔体之间的平衡导致地面样品中的钛同位素分馏，而同位素轻的钛氧化物和同位素重的熔体共存。但是，尽管在陆地样品中Ti主要是四价的，但在与月球岩浆作用有关的f O ₂处，大约10％的Ti是三价的（〜IW-1）。月球样品中钛的不同价态还可能在未知范围内影响月球玄武岩成岩过程中Ti的稳定同位素分馏。我们使用气体混合炉进行了实验研究，研究了在不同的f O _2下形成氧化钛的影响母玄武岩成岩过程中Ti稳定同位素分馏的研究 在每次实验期间，两个平衡的本体组成同时平衡，以确保可比性。用EPMA对一个实验进行了研究，以表征实验运行产品的岩石学特性，而对第二个实验进行了压碎，并手工挑选，分离和消化了加工相（即氧化物，硅酸盐和玻璃）。在使用改良的HFSE化学方法将Ti与基质和干扰元素分离之前，将每个样品的等分试样与Ti双掺钛混合。我们的研究表明，从空气到IW-1的7个样品中的f O ₂依赖的分馏，尤其是∆ ⁴⁹ Ti_轻铝熔体和∆ ⁴⁹ Ti从氧化态到还原态，_{芳铝石-邻苯二酚的}分馏程度更高（分别为-0.092±0.028--0.200±0.033‰和-0.089±0.027--0.250±0.049‰），而∆ ⁴⁹ Ti邻苯二甲酚_熔体仅显示出较小的分馏作用（ -0.002±0.017-0.050±0.025‰）。这项研究的结果表明，母马玄武岩成岩过程中的Ti同位素分馏预计是氧化还原依赖性的，通常确定为陆地f O _2的矿物熔体分馏可能不会直接应用于月球环境。这对于评估由于月岩岩浆作用引起的Ti同位素分馏非常重要，与较氧化的陆地岩浆岩相比，该过程在更多的还原条件下进行。